After disabling Filevault 1, is it possible to enable it again in Lion?

Question

It seems that after disabling Filevault 1 in OS X Lion, there no longer is an option to choose between Filevault 1 and Filevault 2 functionality.

I actually prefer Filevault 1 over Filevault 2, since it does not interfere with my theft protection software and allows me to use a guest account.

Is there a way to enable Filevault 1 again?